The Role of Biomarkers Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) and Vasoactive Intestinal Peptide (VIP) in Chronic and Episodic Migraines: A Meta-Analysis

Table 1

Descriptive characteristics of the included studies.

Code	Author year	Study country	Sample size (cases, control)	Age of cases mean (SD)	Gender of cases (male : female)	Analytical assay/sample used	Key findings
1	Han et al. 2015 [31]	China	Migraine: 133; Chronic: 38; Episodic: 95; Controls: 50	40.86 (11.97)	50 : 11	ELISA plasma	Significantly lower PACAP level in both chronic migraine () and episodic migraine ().
2	Morollon “1” et al. 2014 [16]	Spain	Migraine: 81; Chronic: 81; Controls: 33	46.2 (11.0)	1 : 24	ELISA plasma	There was a significantly higher VIP level in chronic migraine than in healthy controls ().
3	Morollon “2” et al. 2016 [17]	Spain	Migraine: 121; Chronic: 86; Episodic: 35; Controls: 32	Chronic migraine: 42.8 (13.4); Episodic migraine: 43.9 (13.4)	0 : 121	ELISA serum	There was a significantly higher VIP and PACAP in chronic migraine () and no difference in episodic migraine and controls (). Statistically nonsignificant differences of VIP and PACAP between chronic and episodic migraines ().
4	Pereda et al. 2020 [3]	Spain	Migraine: 199; Chronic: 101; Episodic: 98; Controls: 97	41 (10)	1 : 9	ELISA serum	VIP and PACAP were significantly elevated in chronic and episodic migraine compared to controls.
5	Togha et al. 2021 [25]	Iran	Migraine: 59; Chronic: 36; Episodic: 23; Controls: 30	38.5	18 : 71	ELISA serum	VIP and PACAP were significantly higher ( and 0.043, respectively) in episodic migraine, while there were no significant differences in the case of chronic migraine.

ELISA: enzyme-linked immunosorbent assay; PACAT: pituitary adenylate cyclase-activating polypeptide; VIP: vasoactive intestinal peptide.